Contamination of soils and water by halohydrocarbons is a major health concern. Although some of these compounds are biodegradable, others are unusually persistent and their degradation frequently requires long periods of acclimation. The long term objectives and principle aim of the proposed research is to investigate the evolution of biodegradation and establish the importance of gen exchange in the in situ development of biodegradative traits among gram negative bacteria. Research proposed will identify mechanisms by which: (1) biodegradative capacity is established and magnified in hydrocarbon contaminated soil and water; (2) biodegradative traits are maintained or lose in natural bacterial communities; (3) inter- strain and inter-species transfer of biodegradative traits occurs within bacterial communities. The usefulness of gene probes, transposons, and restriction fragment length polymorphism to assess lateral gene transfer between well characterized isolates will be established. And the influence of environmental determinants including quality and quantity of halohydrocarbons, water availability, ph, and temperature on growth, survival, and persistence of biodegraders and biodegradation capacity will be established. Anticipated results will answer basic ecological questions relative to evolution of biodegradative capacity under natural and simulated natural conditions and will facilitate development of methods by which natural environments can be manipulated to maintain or enhance local biodegradative activity.